1. Field
The present invention relates to an apparatus and a method for processing an outer circumferential surface of a piston.
2. Description of Related Art
It is desired that a shape of an outer circumferential surface of a piston reciprocating in an internal combustion engine is formed so as to bring a constant gap to an inner surface of a cylinder at all positions in view of thermal expansion at combustion and so on. Therefore, it is needed to process a shape of an outer circumferential surface of a piston material three-dimensionally (to process it into a shape having a three-dimensional surface change to an ellipsoidal reference circumferential surface or a circular reference circumferential surface). Conventionally, such a process was done by use of a turning machine (U.S. Pat. No. 6,666,118) or a cutting machine (Japanese Patent Application Laid-Open No. H5-84602).